The present invention relates to belt lacers of the type used to fasten connectors onto the ends of conveyor belts and the like, and in particular to a portable belt lacer.
When fastening belt connectors or their connective fasteners onto the ends of conveyor belts, power belts, or the like, one problem is ensuring a precise penetration of the holding staples, the tips of which have been placed in the holes of the upper fastener shank, into the holes of the lower fastener shanks that are positioned in the bending die, i.e., subsequent to penetration of the belt end concerned. In the course of fastening the connective fasteners, the upper fastening shanks are pressed down upon the surface of the belt. A precise motion of the fastener shanks towards one another must be ensured both for different wall thicknesses, as well as for different belt elasticities and other belt characteristics.
For this reason, the user often selects a sufficiently large amount of play between the fastening shanks and associated connector holes. However, this results in diminished fastening strength of the connective fasteners and ultimately of the belt connectors relative to fastener location and hold. If connective fasteners of relatively strong material are used instead, positioning of the connective fasteners during fastening of the connective fasteners is simplified and, in particular, a relatively slight amount of xe2x80x9chole playxe2x80x9d is made possible. However, the deformative forces required during attachment of such belt connectors are quite high.
DE 41 40 743 A1 discloses a device of the above-named type in which connective fasteners of comparatively thin sheet metal material are used, whereby the eye loops are produced from the sheet metal material as folded loops of U-shaped cross section to increase resistance to stress and wear. This thin sheet metal material requires guide holes for the holding staples with the smallest possible amount of guide play in order to achieve a flawless seating and hold of the connective fasteners and, consequently, for the belt connectors, onto the ends of the belts. The complicated interaction of the individual centering agents is a disadvantage of this device, which also causes the device to be quite expensive in construction. Aside from this, the rod, which can be slid into the bending die and which the eye loops of the connective fasteners wrap around, performs no centering function in this device. Finally, the device does not allow itself to be converted to other sizes of belt connectors. Furthermore, it does not allow precise contact of the connective fasteners in the channel of the press head upon initial centering of the press head over the bending die via a peg connected to the press head, which peg can be placed in a centering bore of the bending die.
In contrast to such prior art devices, in the present invention, because of the tight motion tolerances desired, diverse centering devices are provided in order to guarantee a flawless introduction of the holding staples into the guide holes of the lower fastener shank upon driving in the holding staples. Hence, one side of the bending die has centering lamellae or elements between the eye loops that connect the fastener shanks of the respective connective fasteners, and the other side has centering wedges or pins that fit within V-shaped recesses on the back side of the fastener shanks lying upon the die. Additionally, the underside of the press head is provided with a centering stop for the back sided end of the upper fastener shank of the connective fasteners.
One object of the invention is to provide a device of the above-named type in such a way that an optimal centering of the belt connectors can be achieved during their fastening onto the belt using agents of simple construction.
Another object is achieved for a device of the above-mentioned type in that the centering of the connective fasteners is achieved via the means which articulate between the eye loops, as well as via the rod, whereby the centering rod that is slid into the bending die positions the connective fasteners against the centering means found between the eye loops.
In the device according to the present invention, the rod therefore takes on the function of a component which facilitates centering. Upon sliding the rod into the connective fasteners that have been placed upon the bending die, the rod contacts the eye loops of the connective fasteners and positions the connective fasteners against the centering means or members which are found between the eye loops. The centering members arranged between the eye loops are constructed as pins according to a particular embodiment of the invention. Aside from these centering means, specifically the rod and the pins, the device according to the present invention fundamentally requires no further centering mechanisms.
Since the centering members that fit between the eye loops are constructed as pins according to the preferred embodiment of the invention, these centering members require only a small amount of space, such that sufficient room remains for sliding in the rod. The rod represents a fixed pivotal axis for the connective fasteners, in that the possibility exists to bend those fastener shanks of the connective fasteners, which are impinged via upper die and the connective fasteners, around this fixed axis until these fastener shanks contact the belt. In this fashion, it is ensured that said fastener shanks are bent in a specific, predefined manner, in a position in which the holes of the corresponding fastener shanks, which incorporate the belt between them, are aligned with one another.
According to a particular embodiment of the invention, it is foreseen that the rod is slidably mounted in the bending die, parallel to the axis of the rod. On the one hand, this enables optimization of rod position relative to the connective fasteners, specifically to the eye loops of the connective fasteners, such that the rod lies against the eye loops and thus takes on the function of a centering means or member. On the other hand, the adjustability of the rod allows different sizes of belt connectors to be processed in the same bending die. The various sizes of belt connectors differ in the length of the fastener shanks in particular, so that, at an unchanged position of the connective fasteners relative to the bending die, only the position of the rod needs to be changed for the purpose of contacting the eye loops of the connective fasteners.
In particular, the rod is mounted such that it is continuously slidable in parallel, although the adjusting agents for sliding the rod are self-limiting. This ensures for all rod positions that the rod will not slide in the direction of any transverse forces acting upon it whenever such transverse forces occur.
As a general rule, it is not necessary to provide for more than two different parallel rod positions, in order to position more than two sizes of belt connectors. In order to bring about the positioning of two belt connector sizes, axial translocation or shifting of the mounting elements for the rod, combined with a rotational motion of the mounting elements by 180 degrees, are advantageously provided. The rod can thus be slid into the same bores of the mounting elements.
According to a preferred embodiment of the invention, it is provided that the rod is mounted in aligned bore holes of mounting elements that can be slid by means of the adjusting members, whereby the mounting elements have stops for the belt end that has been placed between the fastener shanks of the connective fasteners. A corresponding parallel repositioning of the stop for the current belt end to be processed therefore goes along with parallel repositioning of the rod.
According to one embodiment of the invention, it is foreseen that the bending die has reversing recesses for reverse bending the tips of the holding staples, whereby the reversing recesses are of shallow construction. In the area of the connective fasteners, the belt connection is consequently very shallow in relation to conveyor belt thickness. The bending forces generated during the reversing of the tips of the holding staples are also absorbed by the centering members. Shallow reversing recesses are understood to mean those which have no greater depth than the thickness of the respective fastener shanks relative to their dimension in the direction of conveyor belt thickness. Contrary to various prior art, it is, in particular, not necessary to bend back the end sections of the holding staples in the direction of the respective fastener shanks so that these end sections traverse holes in the fastener shanks.
Based on the centering of the connective fasteners via the centering members according to the present invention, one can forego the need for centering means or agents in the area of the upper die. To this extent, it is considered expedient for the upper die to have a planar upper die face, in particular to have a planar upper die face that strikes the holding staples at an angle. This angle corresponds to less than 10 degrees, whereby the upper die is oriented such that, on the basis of the design of its inclined upper die face, it initially strikes that area of the respective holding staples that faces the free end of the fastener shank. Correspondingly, the press head, which comes into contact with the fastener shanks, preferably also has an inclined contact face. As a result, upon placing the press head on the belt connector and/or upon inducement of an upper die force, those areas of the belt connector that face away from the eye loops are contacted or impinged first. The main compressive forces are thus introduced into the belt connector at a large distance from the rod.
It is considered particularly advantageous if the press head and the bending die can be centered by means of pegs, whereby the respective peg is spring mounted. On the basis of this construction, it is, in particular, possible to use connective fasteners having a V-shaped design, rather than a U-shaped design, in their initial configuration, i.e., prior to bending together. Placement of the press head onto the holding staples can occur with the press head at an inclined arrangement to the bending die corresponding to the open angle of the fastener shank, whereby the peg has not yet centered the press head and the bending die, but is instead retracted into the press head or the bending die in opposition to the force of a spring, depending upon in which of these parts said peg is mounted. Not until the fastener legs have assumed their U-shaped form under the influence of the weight of the press head, or that of an external force applied to the press head, does the peg, under the force of the spring, move into the complementary bending die to center the parts.
Further features of the invention are presented in the description of the figures and in the figures themselves, whereby it is noted that all individual features and all combinations of individual features are essential to the invention.
These and other advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written specification, claims and appended drawings.